Air pollution raises risk of type 2 diabetes, says landmark Indian study

Inhaling Polluted Air Increases Risk of Type 2 Diabetes in India

A recent study conducted in India has found that inhaling polluted air increases the risk of type 2 diabetes. The research, which took place in Delhi and Chennai, discovered that exposure to high levels of PM2.5 particles in the air led to elevated blood sugar levels and an increased incidence of type 2 diabetes.

Understanding PM2.5 Particles

PM2.5 particles are extremely small, measuring 30 times thinner than a strand of hair. When inhaled, these particles can enter the bloodstream and cause various respiratory and cardiovascular diseases.

This study, part of ongoing research into chronic diseases in India since 2010, is the first to specifically investigate the link between exposure to ambient PM2.5 and type 2 diabetes in India. It is worth noting that India is one of the worst countries in the world for air pollution.

According to the study, the average annual PM2.5 levels in Delhi ranged from 82-100μg/m³, while in Chennai, the range was 30-40μg/m³. These levels are significantly higher than the World Health Organization’s recommended limit of 5μg/m³. India’s national air quality standards allow for levels up to 40μg/m³.

High Burden of Non-Communicable Diseases in India

India faces a high burden of non-communicable diseases, including diabetes, hypertension, and heart disease. A paper published in The Lancet in June revealed that 11.4% of the population, equivalent to 101 million people, are living with diabetes in India. Additionally, approximately 136 million individuals are pre-diabetic. In comparison, the average diabetes prevalence in the European Union was 6.2% in 2019 and 8.6% in the UK in 2016.

The Lancet study also highlighted that diabetes prevalence in India is higher than previously estimated and that there is a greater number of diabetics in urban areas compared to rural regions.

The BMJ study followed a cohort of 12,000 men and women in Delhi and Chennai from 2010 to 2017. The researchers periodically measured their blood sugar levels and used satellite data and air pollution exposure models to determine the air pollution levels in their respective localities during that period.

The study found that one month of exposure to PM2.5 particles led to elevated blood sugar levels, while prolonged exposure of one year or more increased the risk of developing diabetes. For every 10μg/m³ increase in the annual average PM2.5 level in the two cities, the risk for diabetes increased by 22%.

Siddhartha Mandal, lead investigator of the study and a researcher at the Centre for Chronic Disease Control in Delhi, explained that Indians are more prone to diabetes due to their low BMI and high proportion of fat. He also emphasized that the addition of air pollution, along with lifestyle changes over the past few decades, has contributed to the increasing burden of diabetes in India.

Dr. V Mohan, chairman of the Madras Diabetes Research Foundation and one of the authors of the paper, stated that this study is an eye-opener because it reveals pollution as a new cause of diabetes, challenging previous assumptions about the factors contributing to higher diabetes prevalence in urban areas compared to rural regions.

Another study conducted on the same cohort in Delhi found that average annual exposure to PM2.5 particles in the city (92μg/m³) led to increased blood pressure levels and a higher likelihood of developing hypertension.

Both studies demonstrate that the elevated levels of PM2.5 particles in the air in Indian cities contribute to the development of diabetes and hypertension, which can lead to atherosclerosis, heart attacks, and heart failures.

PM2.5 particles contain sulfates, nitrates, heavy metals, and black carbon, which can damage the lining of blood vessels and increase blood pressure by stiffening the arteries. These particles can also deposit in fat cells, causing inflammation and directly impacting the heart muscle. Dr. Dorairaj Prabhakaran, cardiologist and executive director of the Centre for Chronic Disease Control, explained that PM2.5 particles act as endocrine disruptors, hindering insulin production and its effectiveness in the body.

The study also highlights the rise of hypothyroidism, polycystic ovarian syndrome (PCOS), and gestational diabetes in urban India. Pollution disrupts the endocrine system responsible for producing hormones in the body, potentially contributing to these conditions.